JP6747206B2 - Tire manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a tire having excellent uniformity.

Japanese Unexamined Patent Publication No. 7-52277 discloses a carrier device for carrying a ring-shaped tread ring in a tire preforming process. The carrying device includes a plurality of segments that hold the outer peripheral surface of the tread ring. The circumferential length and the axial width of this segment are set to predetermined values. By holding the tread ring with this segment, it is possible to suppress the occurrence of a deviation when the tread ring and the carcass ply member are united.

Japanese Patent Laid-Open No. 7-52277

It is desirable that the segment of such a transporting device is provided with an abutting surface having a shape close to the outer peripheral surface shape of the tread ring. Deformation of the tread ring can be suppressed by holding the outer peripheral surface of the tread ring with the segment having such a contact surface. By using such a segment, the uniformity of the tire can be improved. However, when using such a segment, it is necessary to replace the segment according to the outer diameter of the tire. Since this segment requires positional accuracy in the circumferential direction, the axial direction and the radial direction, it is not easy to replace the segment. In particular, in a mixed-flow production line in which a wide variety of tires are produced, such replacement of segments is likely to impair productivity.

An object of the present invention is to provide a tire manufacturing method that improves uniformity while suppressing a decrease in productivity.

The tire manufacturing method according to the present invention includes a preforming step of forming a raw cover that is vulcanized to obtain a tire.
The preforming step is
(1) A carcass molded body in which a carcass member and a bead member are attached to each other to form a tubular shape, and a tread molded body in which a tread member is formed into a ring shape are prepared, and a transfer device is provided on an outer peripheral surface of the tread molded body. And a carrying step of carrying the tread molded body to the outside in the radial direction of the carcass molded body, and (2) bonding the tread molded body held by the carrying device to the outer peripheral surface of the carcass molded body. And the raw cover is formed.
The transfer device includes a frame having an opening and a plurality of segments located in the opening. The plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molding and are movable in the radial direction of the outer peripheral surface. Each segment has a clamping surface that abuts the outer peripheral surface of the tread compact. The clamp surface is formed from at least two area surfaces having different radii of curvature in a cross section perpendicular to the axial direction.

Preferably, in the clamp surface, the radius of curvature of one region surface located on the circumferential center side is smaller than the radius of curvature of another region surface located adjacent to the one region surface and located on the circumferential end side. ing. The one area surface is located radially outside of the other area surface.

Preferably, the outer diameter of the tire is 230 (mm) or more and 395 (mm) or less.

The conveying device for a tread compact according to the present invention is a device for conveying a tread compact having a ring-shaped tread member made of unvulcanized rubber. The carrying device includes a frame having an opening and a plurality of segments located in the opening. The plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molding and are movable in the radial direction. Each segment is provided with a clamping surface that abuts the outer peripheral surface of the tread compact. The clamp surface is formed by at least two or more area surfaces having different radii of curvature in a cross section perpendicular to the axial direction.

Preferably, in the clamp surface, the radius of curvature of one region surface located on the circumferential center side is smaller than the radius of curvature of another region surface located adjacent to the one region surface and located on the circumferential end side. ing. The one area surface is located radially outside of the other area surface.

Preferably, the centers of the radii of curvature of the two or more area surfaces are located on a radial straight line along which the segment moves.

Preferably, the carrying device includes a spacer detachably attached to the clamp surface. The spacer has an inner surface facing inward in the radial direction and an outer surface facing outward in the radial direction. In the cross section perpendicular to the axial direction, the inner side surface is formed with the radius of curvature of the other area surface. With the spacer attached to the clamp surface, the other area surface and the inner side surface are located on the same arc.

In the tire manufacturing method according to the present invention, the outer peripheral surface of the tread molded body is clamped by the area surface having a shape close to the shape of the outer peripheral surface of the tread molded body among the area surfaces having different curvature radii of the clamp surface. This manufacturing method suppresses the deformation of the tread compact due to the contact of the segments. By using this tread molded body, the uniformity of the tire can be improved.

FIG. 1 is a conceptual diagram showing a molding apparatus for a tire manufacturing method according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing a carrying device of the molding apparatus of FIG. FIG. 3 is an explanatory view showing a clamp of the transport device of FIG. FIG. 4 is an explanatory view showing a clamp of another conveying device of the molding apparatus of FIG.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

FIG. 1 shows a pneumatic tire forming apparatus 2. The molding device 2 includes a first molding device 4, a second molding device 6, and a transfer device 8.

The first molding device 4 includes a pedestal 14, a first drum 16, and a pair of bead receiving portions 18. Although not shown, the first molding device 4 includes a bladder between the pair of bead receiving portions 18 in the axial direction. The bladder may expand radially outward and contract radially inward. The gantry 14 supports the first drum 16. The first drum 16 has a cylindrical shape. The axial length of the first drum 16 is expandable. Each of the pair of bead receiving portions 18 has a ring shape. The axial distance between the pair of bead receiving portions 18 can be changed. The first drum 16 and the pair of bead receiving portions 18 are rotatable about the axis of the first drum 16 as a rotation axis.

The second molding device 6 includes a frame 22 and a second drum 24. The gantry 22 supports the second drum 24. The second drum 24 has a cylindrical shape. The second drum 24 is rotatable about its axis. The outer peripheral surface of the second drum 24 can be expanded and contracted in the radial direction.

The transfer device 8 includes a rail 26, a moving base 28, an annular frame 30, and a plurality of clamps 32. The rail 26 extends from the first molding device 4 to the second molding device 6. The moving table 28 is movable along the rail 26. The annular frame 30 is placed and fixed on the moving table 28. The annular frame 30 is movable along the rail 26 between a position arranged radially outside the first drum 16 and a position arranged radially outside the second drum 24.

As shown in FIG. 2, the annular frame 30 is formed with an opening 31 penetrating in the axial direction. The cross-sectional shape of the opening 31 perpendicular to the axial direction is circular. The axis of the opening 31 coincides with the axis of the first drum 16 and the axis of the second drum 24. The circumferential direction of the opening 31 is parallel to the circumferential direction of the first drum 16 and the circumferential direction of the second drum 24. In the following description, unless otherwise specified, the circumferential direction, the axial direction, and the radial direction represent the circumferential direction, the axial direction, and the radial direction of the opening 31.

A plurality of clamps 32 are arranged on the inner peripheral surface of the opening 31. The plurality of clamps 32 are arranged at equal intervals along the circumferential direction. In this transfer device 8, a clamp 32 is attached to the inner peripheral surface of the opening 31. The plurality of clamps 32 are integrally rotatable with the axis of the opening 31 as a rotation axis.

Each clamp 32 comprises a body 34 and a segment 36. The dashed-dotted line Lr in FIG. 2 represents a straight line extending through the center of the opening 31. The straight line Lr is a straight line in the radial direction of the opening 31. The segment 36 can move along the straight line Lr with respect to the main body 34. In other words, the segment 36 can move in the radial direction of the opening 31.

The plurality of segments 36 can be expanded and contracted in the radial direction at the same movement distance. In other words, these segments 36 can move in the radial direction while being aligned on the circumference of the concentric circle of the opening 31. The segment 36 comprises a clamping surface 38 facing inward in the radial direction.

In FIG. 3, the segment 36 is shown with a portion of the body 34. FIG. 3 shows the segment 36 as viewed in the axial direction. In FIG. 3, the segment 36 has a line-symmetrical shape with respect to the straight line Lr. The clamp surface 38 includes a clamp surface 38a as an area surface, a pair of clamp surfaces 38b as another area surface, and a pair of clamp surfaces 38c as still another area surface. The clamp surface 38a is located inside the segment 36 in the circumferential direction. The pair of clamp surfaces 38b are adjacent to the outer side of the clamp surface 38b in the circumferential direction. The pair of clamp surfaces 38c are adjacent to the outer side of the clamp surface 38b in the circumferential direction.

Reference sign Ca in FIG. 3 represents an arc of the contour of the clamp surface 38a. The arrow Ra represents the radius of curvature of the clamp surface 38a. The point Pa represents the center of the arc Ca. Reference symbol Cb represents an arc of the contour of the clamp surface 38b. The arrow Rb represents the radius of curvature of the clamp surface 3b. The point Pb represents the center of the arc Cb. Reference symbol Cc represents an arc of the contour of the clamp surface 38c. The arrow Rc represents the radius of curvature of the clamp surface 38c. The point Pc represents the center of the arc Cc. In FIG. 3, for convenience of explanation, the radii of curvature Ra, Rb, and Rc are shown smaller than the actual ones.

The radius of curvature Ra of the clamp surface 38a is smaller than the radius of curvature Rb. The clamp surface 38a is formed radially outward of the arc Cb. The radius of curvature Rb is smaller than the radius of curvature Rc. The clamp surface 38b is formed radially outside the arc Cc. The center Pa of the arc Ca, the center Pb of the arc Cb, and the center Pc of the arc Cc are located on the straight line Lr.

A method of manufacturing a tire using this molding apparatus 2 will be described. This tire manufacturing method includes a preforming step and a vulcanization step. The preforming step includes a first forming step, a second forming step, a conveying step, and a combining step. In this preforming step, members forming each part of the tire are combined to form a raw cover.

In the first molding step, a carcass ply member, a bead member and the like are wound around the outer periphery of the first drum 16 and the bead receiving portion 18 shown in FIG. A cylindrical carcass molded body 44 is formed from the carcass ply member, the bead member, and the like wound in this manner. The axial direction, the circumferential direction, and the radial direction of the carcass molded body 44 correspond to each of the first drums 16.

In the second molding step, a tread member, a belt member, a band member, etc. are wound around the outer periphery of the second drum 24. A cylindrical tubular tread molding 46 is formed from the tread member, the belt member, the band member, and the like wound in this manner. The axial direction, the circumferential direction, and the radial direction of the tread molded body 46 correspond to each of the second drums 24.

In the carrying step, the carcass molded body 44 and the tread molded body 46 are prepared. The transfer device 8 moves toward the second molding device 6. The transport device 8 positions the segment 36 radially outside the tread molding 46. The segment 36 moves inward in the radial direction and contacts the outer peripheral surface of the tread molding 46. The transport device 8 holds the tread compact 46 with the clamp 32. The diameter of the second drum 24 is reduced, and the second drum 24 is separated from the inner peripheral surface of the tread molding 46. The transport device 8 transports the tread compact 46 to the outside of the carcass compact 44 in the radial direction.

Although not shown in the drawing, the bladder of the first molding device 4 expands to expand the carcass molded body 44 into a toroidal shape. The tread molding 46 is pressure-bonded to the outer peripheral surface of the carcass molding 44. After this crimping, the segment 36 moves radially outward. The clamp surface 38 separates from the outer peripheral surface of the tread molding 46. In this way, the transport device 8 releases the clamp of the tread compact 46. The transport device 8 moves to a retracted position away from the tread compact 46. The tread molding 46 is further pressure bonded to the outer peripheral surface of the carcass molding 46 with a stitcher (not shown). In this way, the raw cover is obtained.

This raw cover is prepared in the vulcanization step. This raw cover is vulcanized with a mold. A tire can be obtained from the raw cover through this vulcanization. The above-mentioned carcass ply member, bead member, belt member, band member and tread member are vulcanized to form the carcass, bead, belt, band and tread of the tire.

The segment 36 of the transport device 8 includes clamp surfaces 38a, 38b and 38c having different radii of curvature. The clamp surface 38 a, 38 b, or 38 c having the shape closest to the outer diameter shape of the tread molded body 46 contacts the tread molded body 46. The clamp surface 38 abuts while suppressing the deformation of the tread molding 46. The tread molding 46 is made of unvulcanized rubber. The outer peripheral surface of the tread compact 46 is easily deformed. This deformation affects the uniformity of the tire. The transport device 8 can contribute to the improvement of tire uniformity.

In this segment 36, the tread molding 46 is clamped by the clamping surface 38a, 38b or 38c which is close to the shape of the outer peripheral surface of the tread molding 46. As a result, in many tread moldings 46 having different outer diameters, the clamp surface 38 maintains a sufficient contact area. The clamp 32 can suppress the positional deviation of the tread molding 46 and hold it stably.

The tread compact 46 is pressed against the carcass compact 44 while the segments 36 suppress the deformation of the tread compact 46. Therefore, the positional displacement between the carcass molded body 44 and the tread molded body 46 is suppressed. From this point of view, the transport device 8 can also contribute to improving the uniformity of the tire.

The segments 36 press-fit the tread compact 46 to the carcass compact 44 while suppressing the deformation of the tread compact 46. In the uniting step, the deformation of the tread compact 46 is suppressed, so that a gap is suppressed from being formed between the carcass compact 44 and the tread compact 46. The carrying device 8 suppresses air from remaining between the carcass molded body 44 and the tread molded body 46.

In this segment 36, the center Pa of the radius of curvature Ra, the center Pb of the radius of curvature Rb, and the center Pc of the radius of curvature Rc are located on the straight line Lr. In other words, the center Pa, the center Pb, and the center Pc are located on the straight line in the radial direction along which the segment 36 moves. As a result, the segment 36 moves so that the axis of the tread compact 46 does not shift in many tread compacts 46 having different outer diameters. As a result, the positional displacement between the carcass molded body 44 and the tread molded body 46 is suppressed. The transport device 8 contributes to improve the uniformity of the tire.

In the carrying device 8, the tread moldings 46 having different outer diameters can be held without changing the shape of the segment 36. The carrier device 8 contributes to improvement in productivity. The carrying device 8 is suitable for a mixed flow production line in which tires having different outer diameters are produced.

The outer diameter of the tire varies greatly depending on the application. However, the outer diameter of the passenger car tire is approximately in the range of 230 (mm) to 395 (mm). This outer diameter range is relatively narrow. By using the clamp 32 in this range, a tire having excellent uniformity can be manufactured without changing the mold. This carrier device 8 is particularly suitable for a method of manufacturing a passenger car tire.

This segment 36 is provided with three area surfaces having different radii of curvature of the clamping surfaces 38a, 38b and 38c. The clamp according to the present invention is not limited to this. The clamp according to the present invention may be provided with two or more area surfaces having different radii of curvature. The clamping surface may include four or more area surfaces having different radii of curvature.

4(a) and 4(b) show a clamp 50 of another transfer device 48 used in the manufacturing method according to the present invention. The carrying device 48 includes a clamp 50 instead of the clamp 32 of the carrying device 8. The transfer device 48 has the same configuration as the transfer device 8 except that the clamp 50 is provided. Here, the configuration of the transport device 48 different from that of the transport device 8 will be described, and the description of the same configuration as the transport device 8 will be omitted. Further, the same configuration as the transport device 8 will be described using the same reference numerals as the transport device 8.

The clamp 50 includes a spacer 40 and a spacer 42 in addition to the body 34 and the segment 36.

In FIG. 4( a ), a spacer 40 is shown with a portion of the body 34 and the segment 36 as seen axially. The spacer 40 has an inner surface 40a facing inward and an outer surface 40b facing outward in the radial direction. The contour of the inner surface 40a is formed by an arc having the same radius of curvature Rb as the clamp surface 38b. The contour of the outer side surface 40b is formed by an arc having the same radius of curvature Ra as the clamp surface 38a.

The spacer 40 is detachably attached to the clamp surface 38a. This mounting method is not particularly limited. For example, circumferential and axial positioning pins are inserted into the outer surface 40b and the clamp surface 38a for positioning. The spacer 40 is fixed to the segment 36 with a screw. The outer surface 40b of the spacer 40 is in contact with the clamp surface 38a. At this time, the inner side surface 40a is located on the same arc Cb as the pair of clamp surfaces 38b. By mounting the spacer 40, a clamp surface 52 is formed from the inner surface 40a and the pair of clamp surfaces 38b.

In FIG. 4( b ), the spacer 42 is shown together with the spacer 40, as seen in the axial direction. The spacer 42 includes an inner side surface 42a facing the inner side and an outer side surface 42b facing the outer side in the radial direction. The contour of the inner side surface 42a is formed by an arc having the same radius of curvature Rc as the clamp surface 48c. The contour of the outer side surface 42b is formed by an arc having the same radius of curvature Rb as the clamp surface 48b. The spacer 42 is detachably attached to the clamp surface 38b. This mounting method is similar to that of the spacer 40. The outer surface 42b of the spacer 40 is in contact with the clamp surface 38b and the inner surface 40a of the spacer 40. At this time, the outer side surface 42a is located on the same arc Cb as the pair of clamp surfaces 38c. By mounting the spacer 42, a clamp surface 54 is formed from the inner side surface 42a and the pair of clamp surfaces 38c.

In FIG. 4B, it suffices that the clamp surface 54 be formed, and a spacer in which the spacer 40 and the spacer 42 are integrated may be used. Further, the spacer 42 may be attached to the clamp 32 to which the spacer 40 is not attached.

As shown in FIG. 4A, the clamp 50 can abut on the tread molding 46 at the clamp surface 52. The contact area of the clamp surface 52 is wider than the contact area of the pair of clamp surfaces 38b. The clamping surface 52 further provides a sufficient contact area. The deformation of the tread compact 46 can be further reduced. Further, since the tread molded body 46 is pressure-bonded to the carcass molded body 44 while the segment 36 suppresses the deformation of the tread molded body 46, the positional deviation between the carcass molded body 44 and the tread molded body 46 is further suppressed. .. By using the clamp 50, the transport device 48 can further contribute to the improvement of tire uniformity. Furthermore, it is further suppressed that air remains between the carcass molded body 44 and the tread molded body 46.

The spacer 40 is positioned and attached to the clamp surface 38. The clamp surface 38 is accurately positioned in the circumferential direction, the axial direction, and the radial direction with respect to the tread molded body 46. Since the spacer 40 is attached to the clamp surface 38a, it can be easily and accurately positioned. Compared with the mold change of the main body 34 and the segment 36, this mold change can be easily performed with high accuracy in a short time.

The contact area of the clamp surface 54 shown in FIG. 4B is wider than the contact area of the pair of clamp surfaces 3c. As a result, similarly to the case where the spacer 40 is attached, it can further contribute to the improvement of the uniformity of the tire. Further, the residual of air between the carcass molded body 44 and the tread molded body 46 is further suppressed. Moreover, since the spacer 42 is attached to the clamp surface 38b, this mold change can be easily performed with high accuracy in a short time.

Hereinafter, the effects of the present invention will be clarified by examples, but the present invention should not be construed in a limited way based on the description of the examples.

[Example 1]
A raw cover was formed in a preforming step using the conveying device shown in FIGS. 1 to 3. This segment had clamping surfaces of three different radii of curvature. The radius of curvature of one of the clamp surfaces was 340 (mm). The size of the tire obtained from this raw cover was “225/55R19”. Using this transfer device, 60 raw covers were molded. These raw covers were vulcanized to obtain tires.

[Comparative Example 1]
A raw cover was molded in the same manner as in Example 1 except that the segment had a clamp surface with a single radius of curvature and the radius of curvature was 320 (mm). These raw covers were vulcanized to obtain tires.

[RRO evaluation]
RRO (radial runout) was measured for these tires. Specifically, RRO was measured on the outer peripheral surface of the tire using a non-contact laser measuring device. From the measured values, the average of each measured value and the standard deviation were obtained. In Table 1, the average value and the standard deviation are represented by an index with Comparative Example 1 being 100. The smaller the index of this average value, the smaller the average value of RRO. The smaller the index of this average value, the better. The smaller the index of this standard deviation, the smaller the variation of RRO. The smaller the standard deviation index, the better.

As shown in Table 1, the manufacturing method of the example has a higher evaluation than the manufacturing method of the comparative example. From this evaluation result, it is clear that the magnitude of the difference between the radius of curvature of the clamp surface and the outer diameter of the tire affects RRO. Further, even in a clamp surface including three area surfaces having different radii of curvature as shown in FIG. 3, a tire excellent in RRO can be obtained by reducing the difference between the radius of curvature of the area surface in contact and the tire outer diameter. It is clear that it can be produced. From this evaluation result, the superiority of the present invention is clear.

The manufacturing method described above can be widely applied to a tire manufacturing method including a preforming step in which the tread molded body is pressure-bonded to the outer peripheral surface of the carcass molded body.

2... Molding device 4... First molding device 6... Second molding device 8, 48... Conveying device 14... Stand 16... First drum 18... Bead receiving part 22 ... Stand 24 ... Second drum 26 ... Rail 28 ... Moving stand 30 ... Annular frame 31 ... Openings 32, 50 ... Clamp 34 ... Main body 36 ... Segment 38, 52, 54... Clamping surface 40, 42... Spacer 44... Carcass molded body 46... Tread molded body

Claims (7)

It is equipped with a preforming step to form a raw cover that is vulcanized to obtain a tire
The preforming step is
(1) A carcass molded body in which a carcass member and a bead member are bonded to each other to have a tubular shape, and a tread molded body in which a tread member has a ring shape are prepared,
A conveying device holds the outer peripheral surface of the tread molded body and conveys the tread molded body to the outer side in the radial direction of the carcass molded body, and (2) the conveyance to the outer peripheral surface of the carcass molded body. The apparatus has a uniting step in which the raw cover is formed by bonding the tread molded body held by the apparatus,
The transfer device includes a frame having an opening, and a plurality of segments located in the opening, and the plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molded body in the radial direction of the outer peripheral surface. It is movable,
Each segment has a clamp surface that abuts the outer peripheral surface of the tread molded body,
A method for manufacturing a tire, wherein the clamp surface is formed by at least two or more area surfaces having different radii of curvature in a cross section perpendicular to the axial direction. In the clamp surface, the radius of curvature of the one area surface located on the center side in the circumferential direction is smaller than the radius of curvature of the other area surface located on the end side in the circumferential direction adjacent to the one area surface,
The manufacturing method according to claim 1, wherein the one area surface is located radially outside of the other area surface. The manufacturing method according to claim 1, wherein the outer diameter of the tire is 230 (mm) or more and 395 (mm) or less. A tread member made of unvulcanized rubber is a conveying device for conveying a ring-shaped tread molded body,
A frame having an opening and a plurality of segments located in the opening are provided, and the plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molded body and are movable in the radial direction,
Each segment has a clamp surface that abuts the outer peripheral surface of the tread molded body,
A conveying device for a tread compact, wherein the clamp surface is formed of at least two region surfaces having different radii of curvature in a cross section perpendicular to the axial direction. In the clamp surface, the radius of curvature of the one area surface located on the center side in the circumferential direction is smaller than the radius of curvature of the other area surface located on the end side in the circumferential direction adjacent to the one area surface,
The transport device according to claim 4, wherein the one area surface is located radially outward of the other area surface. The transport device according to claim 5, wherein the centers of the radii of curvature of the two or more area surfaces are located on a straight line in the radial direction along which the segment moves. Equipped with a spacer that is detachably attached to the clamp surface,
The spacer has an inner surface facing inward in the radial direction and an outer surface facing outward in the radial direction,
In a cross section perpendicular to the axial direction, the inner side surface is formed with the radius of curvature of the other area surface, and in a state where the spacer is attached to the clamp surface, the other area surface and the inner side surface are The transport device according to claim 4, wherein the transport device is located on the same arc.

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